The thermoelectric properties of any material can be characterized by a quantity called figure of merit Z (or dimensionless figure of merit ZT), defined as Z=S2σ/k, where S is Seebeck coefficient, σ is electrical conductivity, and k is total thermal conductivity. It is desirable to construct materials with high ZT values (e.g., having low thermal conductivity k and/or high power factor S2σ). By way of example, such materials can potentially be used to construct high quality power generation devices and cooling devices.